Azeotrope-like compositions of (Z)-1-chloro-3,3,3-trifluoropropene and hydrogen fluoride

ABSTRACT

Disclosed are azeotropic and azeotrope-like mixtures of (Z)-1-chloro-3,3,3-trifluoropropene (1233zd(Z)) and hydrogen fluoride. Such compositions are useful as an intermediate in the production of 1233zd(Z). The latter compound is useful as a nontoxic, zero ozone depleting fluorocarbon useful as a solvent, blowing agent, refrigerant, cleaning agent, aerosol propellant, heat transfer medium, dielectric, fire extinguishing composition and power cycle working fluid.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims domestic priority from commonly owned, U.S.Provisional Patent Application Ser. No. 61/419,322, filed Dec. 3, 2010,the disclosure of which is hereby incorporated herein by reference.

FIELD OF THE INVENTION

The present invention pertains to azeotropic and azeotrope-likecompositions of (Z)-1-chloro-3,3,3-trifluoropropene (cis-1233zd or1233zd(Z)) and hydrogen fluoride (HF).

BACKGROUND OF THE INVENTION

In recent years there has been some concern that some long livedfluorocarbons might be contributing, albeit in a small way, to globalwarming. Consequently, there is a worldwide effort to usefluorine-substituted hydrocarbons which have short atmospheric lifetimeand therefore do not persist in the atmosphere. In this regard,(Z)-1-chloro-3,3,3-trifluoropropene (1233zd(Z)) having low globalwarming potential, is being considered as a replacement for somefluorocarbons such as 141b in solvents and as a blowing agent.

The production of 1223zd(Z) has been the subject of interest to providean environmentally desirable product for use in blowing agents,refrigerants, cleaning agents, aerosol propellants, heat transfer media,dielectrics, fire extinguishing compositions and power cycle workingfluids. It is known in the art to produce fluorocarbons such a 1233zd(Z)by reacting hydrogen fluoride with various hydrochlorocarbon compounds.

Because many CFCs are known to be ozone-depleting compounds, the use ofthese compounds has been curtailed in favor of chemicals that are morecommercially acceptable. In some cases, alternate CFC compounds havebeen found to be both effective and more environmentally friendly.

As one example, 1-chloro-3,3,3-trifluoropropene (1233zd) has been foundto have a wide variety of uses, for example as a heat transfer agent, asa foaming agent, and as a solvent, among other uses. See for example,U.S. Pat. No. 7,833,433, entitled “Heat Transfer Methods Using HeatTransfer Compositions Containing Trifluoromonochloro-propene”, U.S.Patent Publication No. 2008-0207788, entitled “Foaming Agents, FoamableCompositions, Foams and Articles Containing Fluorine SubstitutedHalogens, and Methods of Making the Same”, and U.S. Pat. No. 6,362,383,entitled “Hydro-Fluorination of Chlorinated Hydrocarbons”, whichdisclose examples of such uses.

The compound 1233zd may be produced by a number of different methods.See, for example, U.S. Pat. No. 7,829,747, entitled “Process forDehydrofluorination of 3-chloro-1,1,1,3-tetrafluoropropane to1-chloro-3,3,3-trifluoropropene”; U.S. Pat. No. 5,710,352, entitled“Vapor Phase Process for Making 1,1,1,3,3-pentafluoropropane and1-chloro-3,3,3-trifluoropropene,” U.S. Pat. No. 6,111,150, entitled“Method for Producing 1,1,1,3,3-pentafluoropropane,” and U.S. Pat. No.6,844,475, entitled “Low Temperature Production of1-chloro-3,3,3-trifluoropropene (HCFC-1233zd)”, which describe severalmethods for making 1233zd.

All of the documents cited above are hereby incorporated herein byreference in their entirety.

SUMMARY OF THE INVENTION

It has now been found that an important intermediate in the productionof substantially pure 1233zd(Z), is an azeotrope or azeotrope-likemixture of 1233zd(Z) and hydrogen fluoride (HF). This binaryintermediate, once formed, may thereafter be separated into itscomponent parts by extraction or distillation techniques. The compound1233zd(Z) has a boiling point of about 18° C. and HF has a boiling pointof about 20° C. at standard atmospheric pressure. These azeotrope orazeotrope-like compositions find use not only as intermediates in theproduction of 1233zd(Z), but they are additionally useful as solventsand as compositions for removing surface oxidation from metals.

In addition, the formation of an azeotropic or azeotrope-likecomposition of 1233zd(Z) and HF is useful in separating a mixture of1233zd(Z) and an impurity. When it is desired to separate a mixture of1233zd(Z) and an impurity, HF is added to form an azeotropic mixture of1233zd(Z) and HF, and then the impurity is removed from the azeotropicmixture, such as by distillation, scrubbing or other known means.

One embodiment of the invention provides an azeotropic compositionconsisting essentially of (Z)-1-chloro-3,3,3-trifluoropropene(1233zd(Z)) and hydrogen fluoride (HF).

Another embodiment of the invention provides an azeotropic orazeotrope-like composition which consists essentially of from about 1 toabout 95 weight percent hydrogen fluoride and from about 5 to about 99weight percent 1233zd(Z), which composition has a boiling point of about0° C. to about 60° C. at a pressure of about 3 psia to a pressure ofabout 73 psia. In certain embodiments the composition consists ofhydrogen fluoride and (Z)-1-chloro-3,3,3-trifluoropropene (1233zd(Z)).In certain embodiments, the hydrogen fluoride is present in an amount offrom about 5 to about 90 weight percent. In certain embodiments, thehydrogen fluoride in present in an amount of from about 20 to about 35weight percent. Certain embodiments of the invention have a boilingpoint of from about 0° C. to about 61° C. at a pressure of from about 3psia to about 73 psia.

Another embodiment of the invention provides a method of forming anazeotropic or azeotrope-like composition which consists essentially ofblending from about 1 to about 95 weight percent hydrogen fluoride andfrom about 5 to about 99 weight percent(Z)-1-chloro-3,3,3-trifluoropropene (1233zd(Z)), which composition has aboiling point of from about 0° C. to about 60° C. at a pressure of about3 psia to about 73 psia. In certain embodiments the composition consistsof hydrogen fluoride and (Z)-1-chloro-3,3,3-trifluoro-propene(1233zd(Z)). In certain embodiments, the hydrogen fluoride is present inan amount of from about 5 to about 90 weight percent. In certainembodiments, the hydrogen fluoride in present in an amount of from about20 to about 35 weight percent. In certain embodiments, the hydrogenfluoride is present in an amount of about 26±3 weight percent. Incertain embodiments of the invention the composition has a boiling pointof from about 0° C. to about 61° C. at a pressure of from about 3 psiato about 73 psia. In certain embodiments the composition has a boilingpoint of about 25° C. at a pressure of about 14.7 psia.

In certain embodiments, 1233zd(Z) can be isolated from the azeotropiclike mixture of 1233zd(Z) and HF by extraction of HF. In certainembodiments, the extraction of HF is accomplished using water or otheraqueous solution. In certain embodiments, the extraction of HF isaccomplished using sulfuric acid. In certain embodiments, the extractionof HF is accomplished by distillation, for example by extractivedistillation, or pressure swing distillation.

The azeotropic and azeotrope-like mixtures of(Z)-1-chloro-3,3,3-trifluoropropene (1233zd(Z)) and hydrogen fluoride ofthe present invention are useful as an intermediate in the production of1233zd(Z). This purified material is useful as a nontoxic, zero ozonedepleting chlorofluorocarbon useful as a solvent, blowing agent,refrigerant, cleaning agent, aerosol propellant, heat transfer medium,dielectric, fire extinguishing composition and power cycle workingfluid.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 shows a plot of the vapor pressures of the mixtures formed inExample 1 as measured at 0° C., 25° C., and 60° C.

DETAILED DESCRIPTION OF THE INVENTION

The binary azeotrope of 1233zd(Z) and HF can be formed as described inthe U.S. Pat. No. 7,829,747 where 244fa is dehydrofluorinated to yield1233zd(Z), HF and other components such as(E)-1-chloro-3,3,3-trifluoropropene, hydrogen chloride,1,3,3,3-tetrafluoropropene, 1,1,1,3,3-pentafluoropropane. Upon removalof the other compounds the binary azeotrope of 1233zd(Z) and HF remains.

1233zd(Z) forms azeotropic and azeotrope-like mixtures with HF. Thethermodynamic state of a fluid is defined by its pressure, temperature,liquid composition and vapor composition. For a true azeotropiccomposition, the liquid composition and vapor phase are essentiallyequal at a given temperature and pressure range. In practical terms thismeans that the components cannot be separated during a phase change. Forthe purpose of this invention, an azeotrope-like composition means thatthe composition behaves like a true azeotrope in terms of its constantboiling characteristics and tendency not to fractionate upon boiling orevaporation. During boiling or evaporation, the liquid compositionchanges only slightly, if at all. This is in contrast withnon-azeotrope-like compositions in which the liquid and vaporcompositions change substantially during evaporation or condensation.

One way to determine whether a candidate mixture is azeotrope-likewithin the meaning of this invention is to distill a sample of it underconditions which would be expected to separate the mixture into itsseparate components. If the mixture is a non-azeotrope ornon-azeotrope-like, the mixture will fractionate, i.e., separate intoits various components with the lowest boiling component distilling offfirst, and so on. If the mixture is azeotrope-like, some finite amountof the first distillation cut will be obtained which contains all of themixture components and which is constant boiling or behaves like asingle substance.

Another characteristic of azeotrope-like compositions is that there is arange of compositions containing the same components in varyingproportions which are azeotrope-like. All such compositions are includedby the term azeotrope-like as used herein. As an example, it is wellknown that at different pressures the composition of a given azeotropewill vary at least slightly as does the boiling point of thecomposition. Thus an azeotrope of two components represents a uniquetype of relationship but with a variable composition depending on thetemperature and/or pressure. As is well known in the art, the boilingpoint of an azeotrope will vary with pressure.

As used herein, an azeotrope is a liquid mixture that exhibits a maximumor minimum boiling point relative to the boiling points of surroundingmixture compositions. An azeotrope or an azeotrope-like composition isan admixture of two or more different components which, when in liquidform under a given pressure, will boil at a substantially constanttemperature, which temperature may be higher or lower than the boilingtemperatures of the components and which will provide a vaporcomposition essentially identical to the liquid composition undergoingboiling.

For the purpose of this invention, azeotropic compositions are definedto include azeotrope-like compositions which means, a composition thatbehaves like an azeotrope, i.e., has constant-boiling characteristics ora tendency not to fractionate upon boiling or evaporation. Thus, thecomposition of the vapor formed during boiling or evaporation is thesame as or substantially the same as the original liquid composition.Hence, during boiling or evaporation, the liquid composition, if itchanges at all, changes only to a minimal or negligible extent. This isin contrast with non-azeotrope-like compositions in which during boilingor evaporation, the liquid composition changes to a substantial degree.

Accordingly, the essential features of an azeotrope or an azeotrope-likecomposition are that at a given pressure, the boiling point of theliquid composition is fixed and that the composition of the vapor abovethe boiling composition is essentially that of the boiling liquidcomposition, i.e., essentially no fractionation of the components of theliquid composition takes place. Both the boiling point and the weightpercentages of each component of the azeotropic composition may changewhen the azeotrope or azeotrope-like liquid composition is subjected toboiling at different pressures. Thus, an azeotrope or an azeotrope-likecomposition may be defined in terms of the relationship that existsbetween its components or in terms of the compositional ranges of thecomponents or in terms of exact weight percentages of each component ofthe composition characterized by a fixed boiling point at a specifiedpressure.

The present invention provides a composition which comprises effectiveamounts of HF and 1233zd(Z) to form an azeotrope or azeotrope-likecomposition. By effective amount is meant an amount of each componentwhich, when combined with the other component, results in the formationof an azeotrope or azeotrope-like mixture. The inventive compositionspreferably are binary azeotropes which consist essentially ofcombinations of only HF with 1233zd(Z).

In the preferred embodiment, the inventive composition contains fromabout 1 to about 95 weight percent HF, preferably from about 5 weightpercent to about 90 weight percent HF and most preferably from about 20weight percent to about 35 weight percent HF. In the preferredembodiment, the inventive composition contains from about 5 to about 99weight percent 1233zd(Z), preferably from about 10 weight percent toabout 95 weight percent and most preferably from about 65 weight percentto about 80 weight percent. The composition of the present invention hasa boiling point of about from 0° C. to about 60° C. at a pressure ofabout from 3 psia to about 73 psia. An azeotropic or azeotrope-likecomposition having about 26±3 weight percent HF and about 74±3 weightpercent 1233zd(Z) has been found to boil at about 25° C. and 14.7 psia.The following non-limiting examples serve to illustrate the invention.

EXAMPLE 1

60 g of 1233zd(Z) were dissolved in 40 g of HF to form a heterogeneousazeotrope mixture. This experiment was conducted at 25° C., and at 14.6psia.

EXAMPLE 2

Binary compositions containing solely 1233zd(Z) and HF are blended toform heterogeneous azeotrope mixtures at different compositions. Thevapor pressures of the mixtures were measured at about 0°, 25° and 60°C. and the following results are noticed. Table 1 shows the vaporpressure measurement of 1233zd(Z) and HF as a function of composition ofweight percent HF at constant temperatures of about 0°, 25°, and 61° C.The data show that 1233zd(Z) and HF formed a heterogeneous mixture.

TABLE 1 Pressure versus composition measurements of 1233zd(Z) and HF at0°, 25° and 60° C. HF T = 0° C. T = 25° C. T = 60° C. Wt % Press, psiaPress, psia Press, psia 0 3.2 8.9 28.5 7.3 9.3 24.6 72.8 13.4 9.7 25.272.4 20 9.9 25.5 72.7 26.7 10 25.5 73.4 33.4 10.1 25.5 73.4 56 9.7 24.673.2 75.5 9.3 23.8 69.2 92.4 8.2 20.5 58.8 100 6.9 17.8 52.4

These data also show that the mixture is an azeotrope since the vaporpressure of mixtures of 1233zd(Z) and HF is higher, at all indicatedblend proportions, than 1233zd(Z) and HF alone, i.e., as indicated inthe first and last rows when HF is 0 wt. % and 1233zd(Z) is at 100 wt. %as well as in the last row where 1233zd(Z) is at 0 wt. % and HF is at100 wt. %. The data from Table 1 are also shown in graphic form in FIG.1.

EXAMPLE 3

The azeotropic composition of the 1233zd(Z)/HF mixture is also verifiedby a Vapor-Liquid-Liquid equilibrium (VLLE) experiment. Here 66.6 g of1233zd(Z) are dissolved in 33.4 g of HF to form a heterogeneous mixture(visual observation) at 26° C. The vapor composition, upper liquid (HFrich), and bottom liquid (organic) were sampled. The result shows thatthe azeotropic composition is about 26±3 wt % HF at 26° C.

As used herein, the singular forms “a”, “an” and “the” include pluralunless the context clearly dictates otherwise. Moreover, when an amount,concentration, or other value or parameter is given as either a range,preferred range, or a list of upper preferable values and lowerpreferable values, this is to be understood as specifically disclosingall ranges formed from any pair of any upper range limit or preferredvalue and any lower range limit or preferred value, regardless ofwhether ranges are separately disclosed. Where a range of numericalvalues is recited herein, unless otherwise stated, the range is intendedto include the endpoints thereof, and all integers and fractions withinthe range. It is not intended that the scope of the invention be limitedto the specific values recited when defining a range.

While the present invention has been particularly shown and describedwith reference to preferred embodiments, it will be readily appreciatedby those of ordinary skill in the art that various changes andmodifications may be made without departing from the scope of theinvention. It is intended that the claims be interpreted to cover thedisclosed embodiment, those alternatives which have been discussed aboveand all equivalents thereto.

1. An azeotropic or azeotrope-like composition which consistsessentially of hydrogen fluoride and (Z)-1-chloro-3,3,3-trifluoropropene(1233zd(Z)), which composition has a boiling point of from about 0° C.to about 60° C. at a pressure of from about 3 psia to about 73 psia,wherein the hydrogen fluoride is present in an amount of from about 20to about 35 weight percent.
 2. An azeotropic or azeotrope-likecomposition having about 26±3 weight percent HF and about 74±3 weightpercent 1233zd(Z) having a boiling point of about 25° C. at a pressureof about 14.7 psia.
 3. A method of forming an azeotropic orazeotrope-like composition which consists essentially of blendinghydrogen fluoride and (Z)-1-chloro-3,3,3-trifluoropropene (1233zd(Z)),which composition has a boiling point of from about 0° C. to about 60°C. at a pressure of about 3 psia to about 73 psia, wherein the hydrogenfluoride is present in an amount of from about 20 about 35 weightpercent.
 4. A method of forming an azeotropic or azeotrope-likecomposition which consists essentially of blending hydrogen fluoride and(Z)-1-chloro-3,3,3-trifluoropropene (1233zd(Z)), which composition has aboiling point of from about 0° C. to about 60° C. at a pressure of about3 psia to about 73 psia, wherein the hydrogen fluoride is present in anamount of about 26±3 weight percent.
 5. A method of forming anazeotropic or azeotrope-like composition which consists essentially ofblending hydrogen fluoride and (Z)-1-chloro-3,3,3-trifluoropropene(1233zd(Z)), which composition has a boiling point of about 25° C. at apressure of about 14.7 psia.